The present invention relates to a routing optical matrix switching method and a device for an optical communication. More specifically, the present invention relates to a routing optical matrix switching method and a device for WDM. optical communication networks.
Recently, all developed countries in the world are preparing to establish WDM high-speed fiber communication networks. So those countries need a great number of all-optical cross connections and fiber protection switch-equipment, optical adding/dropping multiplex OADM and optical wavelength route OXC equipment and the like, of which the most vital device is optical matrix switching device. However, optical matrix switching devices available on the market are switched between input fibers and output fibers with high precision machine-driving fiber or driving optical prism, referring to the product catalogs of The USA Dicon fiber Optics Inc, E-TEK Inc and Canada JDS, and also seeing xe2x80x9cOptical Components for WDM Lightwave Networksxe2x80x9d. Proceedings of The IEEE, Vol.85, No.8, p1274-1307, August 1997. The switching rate of the above mentioned machine-driving optical matrix switching is about 0.5-0.7 second. It is difficult and complex to perform Mxc3x97N all-optical cross-connection, although easily achieving 1xc3x97N or 2xc3x97N all-optical cross connection. The Mxc3x97N all-optical cross-connection with the method of conventional optical Crossbar switching network must cause very large insertion loss in the processes of 1xc3x97N fan-out and Mxc3x971 fan-in. It is a problem to be solved urgently in this field to develop a novel all-optical matrix switching, which is suitable for all-optical cross connect equipment, optical adding/dropping multiplex OADM and optical wavelength route OXC equipment in high-speed D-WDM optical communication network.
The purpose of the present invention is to provide a simple and flexible Mxc3x97N optical matrix switching method and device, where M=2m, M=0,1,2 . . . ; N=2n, n=0,1,2 . . . , to greatly reduce the insertion loss of signal beam between input fiber and output fiber and to increase its switching rate. To realize the object, the present invention puts forward a routing optical matrix switching method and device, thereof.
The Mxc3x97N optical matrix switching method of the present invention comprises steps as:
converting M divergent signal beams into collimated light beams;
converting said M collimated random polarization signal beams into linear polarization signal beams;
said linear polarization signal beams are transmitted with routing parallel optical channel in non-block crossbar network, wherein each of M input signal beams in the x-direction is provided with N parallel optical channels in the y-direction, to construct Mxc3x97N parallel transmission optical channels;
routing combining said M parallel transmission optical channels of each group in said x-direction into one parallel optical channel, to construct N parallel output optical channels in y-direction;
for an unidirection routing matrix switching device, coupling directly signal beams transmitted in said N output parallel optical channels into N output fibers;
for a bidirection matrix switching device, reverting N linear polarization beams output from said N output parallel optical channels into N random polarization signal beams; and
coupling said N random polarization signal beams into N output fibers in parallel; and
in above steps, M=2m, N=2n, m and n are nature numbers.
Based on the above-mentioned Mxc3x97N optical matrix switching method, a bidirection and an unidirection optical matrix switching devices can be developed. Bidirection and unidirection optical matrix switching devices are structured with a routing parallel optical channel and a parallel optical channel routing combination, wherein
a. routing parallel optical channel unit, comprising an optical collimated unit of one dimension fiber array, a parallel plane crystal unit and a routing parallel optical channel unit, wherein
the optical collimated unit of one dimension fiber array includes a base-plate with M parallel V-grooves, in which micro-capillary with fiber tails and gradient index lenses are closely leant against front and back of each V-grooves to construct M parallel optical channels, respectively;
the parallel plane crystal unit are composed of four rectangle parallel plane crystals and two wavelength plates, which are arranged in order of the first rectangle parallel plane crystal, the first wavelength plate, the second rectangle parallel plane crystal, the second wavelength plate, and the third and the fourth rectangle parallel plane crystals overlapped with each other; therein, the first wavelength plate is xcex/2 wavelength plate, the half upper layer of the second wavelength plate is a xcex/2 wavelength plate and the other half lower layer is a glass base plate of parallel plane; and
the routing parallel optical channel unit comprises n stages of optical switching arrays and crystal prism units, in which each stage is composed of, in order, one optical switching array and one crystal prism; and
b. the routing combination unit of parallel optical channel, which is coupled with the routing parallel optical channel unit via optical path in space, the bidirection optical matrix switching device orderly includes a xcex/2 wavelength plate array, a routing combination unit of parallel optical channel, an parallel plane crystal unit; unidirection optical matrix switching device orderly includes xcex/2 wavelength plate array, a routing combination unit of, parallel optical channel, and a coupling unit of one dimension fiber array, moreover the last stage of optical switching array in routing combination unit of parallel optical channel and a parallel plane crystal unit are removed, wherein
the xcex/2 wavelength plate array is structured by arranging two pieces of xcex/2 wavelength plates and of glass base-plates, in the same size, into square crossing;
the routing combination unit of parallel optical channels comprises m stages of crystal prisms and optical switching arrays; in which each stage is composed of, in order, one optical switching array and one crystal prism; the parallel plane crystal unit is composed of four rectangle parallel plane crystals and two wavelength plates, which are the same components as those in the parallel plane crystal unit of the routing parallel optical channel unit, but of which the collocation order is equal to rotate the parallel plane crystal unit in the routing parallel optical channel unit over 180xc2x0 along the axis direction of and over 90xc2x0 along the radial direction of light path; and
the coupling unit of one dimension fiber array comprises a base-plate with N parallel V-grooves, in which gradient index micro-lenses and micro-capillary with fiber tails are closely leant against front and back of each V-grooves, respectively, to construct N parallel optical channels; in above steps, M=2m, N=2n, m, n is nature number.
Said optical matrix-switching device is further characterized as:
(1) in said optical collimated unit of one dimension fiber array, the spacing of V-grooves and the outer diameter of gradient index micro-lenses are all equal to the outer diameter d0 of microcapillary with fiber tails, and a flat base as a cover plate is formed and solidified on the top surface of the entire unit;
(2) in said parallel plane crystal unit, the first and the second rectangle parallel plane crystals are identical crystals with the same size, and the third and the fourth rectangle parallel plane crystals, of which the crystal axes are up-down symmetrical with each other, are identical crystals with the same size as well;
(3) in said routing parallel optical channel unit, each stage of optical switching arrays has 2mxc3x972i cells, where i=0,1,2,3 . . . (nxe2x88x921), and each cell, under the external control, can exhibit one of two states corresponding to the natures of glass medium and xcex/2 wavelength plate, or one of three states corresponding to the natures of glass medium, xcex/2 wavelength plate and xcex/4 wavelength plate;
(4) in said routing combination unit of parallel optical channel, each stage of optical switching arrays has 2jxc3x972n cells, where j=mxe2x88x921, . . . 2,1,0, and each cell is provided with natures of the cell mentioned in (3);
(5) said coupling unit of one dimension fiber array is structured with the same as above-mentioned in (1).
In the routing parallel optical channel unit and routing combination unit of parallel optical channel of the above-mentioned optical matrix switching device, said optical switching array can be an optical switching of movable wavelength plate array, or a liquid-crystal optical switching device as well. The crystal prism can be a trapezoid polarization prism as well as a birefringence crystal prism. In comparison with a bidirection optical matrix-switching device, an unidirection optical matrix-switching device is simple, moreover, both the last stage of optical switching array and the parallel plane crystal units. can be left out in routing combination unit of parallel optical channels.
The Mxc3x97N optical matrix switching method and device of the present invention have the following various advantages: low insertion loss, low polarization dependent loss, low cross-talk, simplified, flexible, and scalable. The Mxc3x97N optical matrix switching device can widely be used for varieties of all-optical cross connection, optical add/drop OADM and optical wavelength route OXC equipment in the field of WDM optical communication.